[Avodah] etrog genetics

[Micha Berger via Avodah]

On Mon, Feb 13, 2017 at 11:29:30AM -0800, saul newman wrote:
: https://en.wikipedia.org/wiki/Polymorphism_(biology)    it would seem these
: are like ABO blood types, a factor that doesnt make a new species, but
: shows a certain degree of relation.  i think given there that there were 3
: original species that all citrus descended from, if those bands [pomelo eg]
: dont show up, then there is no pomelo source.

First, something I learned since this post... There are only fourt known
species of non-hybrid citrus fruit: citron, pomelo ("shedock" in British
English), mandarin and papeda.

Eg the grapefruit is a hybrid of sweet orange and pomelo, cross-bred
by HQBH (wind from one plant to another) in Barbados. The orange itself
is a older hybrid, between pomelo and mandarin (and re-crossed a number
of times with each).

Citrons (both esrogim and the multi-fingered varieties) self-pollinate.
So hybrids are likely intentional by human intervantion.

Whether we are worried about breed, rather than species would depends
on whether a fingered citron is kosher, even if only a fingered citron
that by some fluke only has one finger. If any fingered citrons can be
kosher, than breed doesn't seem to matter.

:                                                   am not sure how grafting
: might change the genes found in the fruit , ie what does rootstock have to
: do with genes in the fruits themeselves

It doesn't. Which is why I wrote:
:> Since grafting doesn't change the genetics of the fruit seeds, this is
:> measuring cross-breeding more than eliminating murkav altogether.

An esrog can be genertically pure and still murkav because it or some
ancestor grew on a graft.

But I noticed a happy pattern... Hybridization is unlikely without
human intervention and grafting is obviously impossible. So if you
go somewhere where there are no nearby citrus hybrids of similar type,
I think you could assume the esrogim aren't murkav.

Tir'u baTov!
-Micha

-- 
Micha Berger             For a mitzvah is a lamp,
micha at aishdas.org        And the Torah, its light.
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